JPH0698986A - Sewing machine - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to reduce the vibration of the sewing machine by canceling the vertical inertial force generated by the reciprocating motion of the needle bar. [Structure] When the upper shaft 10 rotates, the needle bar 44 reciprocates up and down via the needle bar crank 13, and the balancer weight 32 whose movement direction is regulated by the slide guide 33 passes through the counter crank 12. Move back and forth. The phase difference between the needle bar crank 13 and the counter crank 12 is 1
Since the needle bar 44 and the balancer weight 32 are arranged at 80 °, the inertial forces cancel each other out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine in which vibration generated by the vertical movement of a needle bar is reduced.

[0002]

2. Description of the Related Art Conventionally, in this type of sewing machine, as shown in the figure, in order to cancel out the inertial force generated by the vertical movement of the needle bar 170, the center of gravity is eccentric from the center of the upper shaft 174. It is known to utilize the centrifugal force of the needle bar crank 172 where is located. This centrifugal force works only in the vertical direction when the needle bar is at the highest point or the lowest point,
It cancels the inertial force of the needle bar, but it also works horizontally when the needle bar is in the middle. Therefore, even if the eccentric mass of the needle bar crank 172 is determined so that the vertical and horizontal exciting forces acting on the sewing machine body are minimized, the exciting force does not become sufficiently small.

Further, as a mechanism for reducing the vibrating force acting on the sewing machine main body to prevent the vibration, there is a practical use method, Sho 60-19277.
The vibration prevention mechanism described in Japanese Patent No. 4 is known. In the vibration preventing mechanism described in this publication, as shown in FIG. 9, an upper shaft 174 is rotatably supported by a sewing machine frame 176, and a needle bar crank 172 rotates on the upper shaft 174 together with the upper shaft 174. Is fixed as. Further, the connecting rod 17 is attached to the needle bar crank 172.
8 is rotatably supported, and a needle bar 170 is supported on the tip of the connecting rod 178 so as to be vertically movable. At this time, the center of gravity G1 of the needle bar crank 172 is eccentric from the axis C1 of the upper shaft 174, and the needle bar 1
The center of gravity G1 of the needle bar crank 172 is fixed so as to be located directly below the axis C1 when 70 is located at the uppermost point.

Further, as the upper shaft 174 rotates, the balancer shaft 180 rotates through the gears 182a and 182b of the same gear ratio that mesh with each other, and the balancer shaft 180 rotates.
The balancer 184 fixed to the shaft also rotates. The center of gravity G4 of the balancer 184 is fixed so as to be located directly below the axis C4 of the balancer shaft 180 when the needle bar 170 is located at the uppermost point.

Here, G1 is the center of gravity of the needle bar crank 172, G2 is the combined center of gravity of the needle bar 170, the needle bar holder 171, and the connecting rod 178, and the needle bar crank 172.
Is M1, the total mass of the needle bar, etc. is M2, the distance between the axis C1 and G1 of the upper shaft 174 is L1, and the upper shaft 17 from the point of supporting the connecting rod 178 of the needle bar crank 172.
4 is L2, the distance between the supporting points of the connecting rod 178 is L3, and the crank ratio is λ (= L
2 / L3). In addition, the mass of the balancer 184 is M
4. Let L4 be the distance between the axis C4 of the balancer shaft 180 and the center G4 of the balancer.

When the upper shaft 174 of the sewing machine having the above structure is rotated at the rotational angular velocity ω, the sewing machine frame 176 is provided.
Horizontal and vertical exciting force Fx, Fy acting on the sewing machine body via a is the case of the lambda is very small, negligible lambda ³ or more components can be expressed by the following equation.

[0007]

[Equation 1]

[0008]

[Equation 2]

Here, M4 L4 = M1 L1, M2
If L2 = 2M1 L1,

[0010]

[Equation 3]

[0011]

[Equation 4]

Therefore, the exciting force can be reduced as compared with the case where the balancer 184 is not used, and the smaller the crank ratio λ, the smaller the exciting force.

[0013]

However, since L2 is determined by the stroke of the needle bar and L3 cannot be made much larger than the size constraint of the sewing machine frame, the crank ratio λ cannot be made too small and is usually 1/4 to 1 /. Takes a value of 2. Therefore, the components of λ ^{3 and} above cannot be ignored, and the vertical exciting force Fy cannot be completely canceled. Also,
Since the balancer 184 is driven by the gear transmission, gear noise is newly generated.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to cancel the vertical inertial force generated by the reciprocating motion of the needle bar, thereby reducing the vibration and suppressing the vibration. To provide a sewing machine.

[0015]

In order to achieve this object, a sewing machine according to claim 1 of the present invention is rotatably supported by a counter crank having a phase difference from a needle bar crank and a counter crank. And a regulation member that regulates the movement of the balancing member to a constant value.

A sewing machine according to claim 2 of the present invention is
A regulation member is provided for regulating the motion of the balance member to swing motion.

Further, the sewing machine according to claim 3 of the present invention is
A regulating member is provided for regulating the movement of the balancing member to a linear movement.

A sewing machine according to a fourth aspect of the present invention includes a counter crank fixed to the upper shaft.

[0019]

In the sewing machine having the above-mentioned structure according to the first aspect of the present invention, when the upper shaft rotates, the needle bar crank and the counter crank rotate in synchronization with each other with a phase difference therebetween.
Further, when the balancing member moves with the rotation of the balancing crank while the movement of the balancing member is regulated to a constant value, the inertial force of the balancing member and the inertial force of the needle bar, the needle bar crank, etc. Cancel each other out. Since it is a crank mechanism, there is little noise.

Further, in the sewing machine according to the second aspect of the present invention, when the balance member is oscillated with the rotation of the balance crank while the movement of the balance member is regulated by the regulating member, The mating member and the inertial forces of the needle bar and the needle bar crank cancel each other out.

Further, in the sewing machine according to the third aspect of the present invention, when the balance member is linearly moved in accordance with the rotation of the balance crank while the movement of the balance member is constantly regulated by the regulating member, the balance occurs. The member and the inertial forces of the needle bar and the needle bar crank cancel each other out.

In the sewing machine according to the fourth aspect of the present invention, the counter crank fixed to the upper shaft rotates with a phase difference from the counter crank, and the counter member and the needle bar or needle bar are rotated. The inertial forces of the crank etc. cancel each other out.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the sewing machine of the present invention will be described below with reference to FIGS.

In the sewing machine, as shown in FIGS. 2 and 3, the upper shaft 10 is rotatably attached to the frame of the sewing machine (not shown). At the left end of this upper shaft 10,
The upper shaft 10 is provided in the central through hole 16 at the center of the counter crank 12.
Is inserted, and the upper shaft 10 is tightened and fixed by the set screw 18. At one end of the counter crank 12,
The end through hole 20 is formed, and the formation position is the upper shaft 10.
The position is off the axis of. A cylindrical pin portion 22 protruding from the needle bar crank 13 is provided in the end through hole 20.
Has been inserted. The needle bar crank 13 is fixed to one end of the counter crank 12 by tightening the pin portion 22 with the set screw 24.
Faces the counter crank 12 with a gap.

Further, the pin portion 22 of the needle bar crank 13
A through hole 28 formed at one end of the balancing connecting rod 26 is inserted in the base portion 22 a of the above, and the balancing connecting rod 26 is rotatable with respect to the needle bar crank 13. The balancer weight 3 is provided in the engagement hole 30 at the other end of the balancing connecting rod 26.
2 is swingably attached.

In the vicinity of the position of the balancer weight 32, the slide guide 3 having a U-shaped cross section.
3 (shown only in FIG. 3) is fixed to the frame of the sewing machine. The cross-sectional shape of the groove formed by the U-shaped central portion of the slide guide 33 is substantially the same as the cross-sectional shape of the balancer weight 32, and the length of this groove is longer than twice the distance r described later. I shall. The slide guide 33 is fixed so that the groove extends vertically straight. The balancer weight 32 is slidably fitted in the groove of the slider guide 33, and the movement direction of the balancer weight 32 is restricted in the arrow direction.

A circular engaging protrusion 34 is provided on the opposite surface of the needle bar crank 13 on the opposite side (the surface opposite to the mounting portion for the balancing connecting rod 26). An engagement hole 35 having a female screw is formed at the center of the engagement protrusion 34. The engagement protrusion 34 is inserted into a through hole 38 formed at the upper end of the needle bar connecting rod 36, and the needle bar connecting rod 3 is formed.
6 is rotatably attached to the needle bar crank 13 by a crankshaft screw 40. Further, a needle bar 44 is swingably mounted via a needle bar holder 46 in a mounting hole 42 formed at the other end of the needle bar connecting rod 36. The needle bar 44 is inserted through a tubular needle bar metal (not shown) fixed vertically to the frame of the sewing machine, and the movement direction of the needle bar 44 is regulated in the arrow direction.
Further, a needle bar thread guide 48 and a needle 50 are attached to the lower end of the needle bar 44.

In the counter crank 12 and the needle bar crank 13, both connecting rods 2 are arranged from the axial center of the upper shaft 10.
The distances to the center of the rotating portions of 6, 36 are both the same distance r. Both connecting rods 26 and 36 have the same shape, and the distances from the axial centers of the counter crank 12 and the needle bar crank 13 to the mounting portions of the balancer weight 32 and the needle bar 44 are the same distance L and are equal. .

Now, the needle bar 44 and the balancer weight 3
Since the movement directions of 2 are regulated in the arrow directions, respectively, when the upper shaft 10 rotates, the needle shaft 44 and the balancer weight 32 make a reciprocating linear movement in the opposite direction. That is,
The needle bar 44 and the balancer weight 32 are in a relationship of being out of phase by 180 degrees. Even if the balancer weight 32 moves, the slider guide 33 is placed at a position where the balancer weight 32 does not drop out of the groove of the slide guide 33.
Is fixed.

Next, referring to FIG. 2, the exciting force generated when the upper shaft 10 rotates will be described. The rotation angle of the upper shaft 10 is θ, and the rotation speed is ω (= dθ / dt). Needle bar 4
4, the mass m of the part that reciprocates linearly, the mass of the balancer weight 32 is m ₀ , the balance crank 12, the needle bar crank 13 and the upper shaft 10 of the needle bar connecting rod 36 side.
The rotating mass around the upper shaft 10 is M, the distance from the axis of the upper shaft 10 to the center of gravity of the rotating mass M is R (not shown), and the rotating mass around the upper shaft 10 on the side of the balancing connecting rod 26 is M ₀ ,
The distance from the axis of the upper shaft 10 to the center of gravity of the rotating mass M ₀ is R ₀ (not shown), and the crank ratio is λ = r / L.

The exciting force f generated by the reciprocating linear motion of the needle bar 44 or the like is

[0032]

[Equation 5]

Similarly, the exciting force f ₀ generated by the reciprocating linear motion of the balancer weight 32 is

[0034]

[Equation 6]

[0035] _{Here, a 2, a 4, a} 6, ··· is as defined above, "-" sign indicates that the motion direction and opposite of the needle bar 44.

The sum of the vertical excitation forces is

[0037]

[Equation 7]

Therefore, if m = m ₀ , the vertical vibration force is completely zero. Further, even in the case of m≈m _0, the exciting force is very small.

Next, the centrifugal force generated around the upper shaft 10 due to the movements of the needle bar connecting rod and the counterbalanced connecting rod will be considered. The centrifugal force F generated by the rotational mass M of the needle bar crank 12 around the upper shaft 10 on the needle bar connecting rod 36 side is: F = MRω ² Similarly, the balancing connecting rod 2 of the counter crank 12
The centrifugal force F ₀ generated by the rotating mass M ₀ around the upper shaft 10 on the 6 side is F ₀ = −M ₀ R ₀ ω ² where the symbol “−” indicates the centrifugal force due to the mass on the needle bar connecting rod 36 side. Indicates that the direction is opposite.

The sum of the exciting forces due to the rotating mass is F + F ₀ = (MR−M ₀ R ₀ ) ω ² , and the exciting force due to the rotating mass is also 0 if MR = M ₀ R _0. You can This is because the needle bar crank 13 and the counter crank crank 12 have the same distance r from the axis of the upper shaft 10 on both the needle bar 44 side and the balancer weight 32 side, and the counter connecting rod 26 is a part of the needle bar connecting rod 36. If the center of gravity of the counter crank 12 and the needle bar crank 13 themselves is made to coincide with the axis of the upper shaft 10, it is possible to easily manufacture a mechanism in which the excitation force is eliminated in this way. Is. In addition, if the balancing connecting rod 26 is the same part as the needle bar connecting rod 36, there is an advantage that the number of parts can be reduced.

Next, the second embodiment will be described with reference to FIGS.
Will be described with reference to.

An eccentric boss portion 56 is formed on the right side surface of the needle bar crank 54, and a central through hole 58 is formed in the eccentric boss portion 56. This central through hole 58
The distal end portion of the upper shaft 10 is inserted through the upper shaft 10, and the needle bar crank 54 is fixed to the upper shaft 10 by tightening the distal end of the upper shaft 10 with a set screw 60. The amount of eccentricity of the eccentric boss portion 56 is r ₀ , and the eccentric boss portion 56 is rotatably inserted with a through hole 64 formed at one end of the balancing connecting rod 62. The balancer weight 32 is swingably attached to the engaging hole 66 at the other end of the balancing connecting rod 62. Eccentricity r
And the distance r ₀ is r> r ₀ .

Further, the pin portion of the crankshaft pin 70 is inserted into the end portion through hole 68 formed at the end portion of the needle bar crank 54, and the crankshaft pin 54 is tightened by the set screw 72. The needle bar connecting rod 36 inserted through the crank shaft pin 54 is rotatably attached to the needle bar crank 54.

The lengths of the balancing connecting rod 62 and the needle bar connecting rod 36 are L ₀ and L, respectively.
And the distance from the axis of the upper shaft 10 of the needle bar crank 54 to the center of the rotating part of both connecting rods 36, 62 is the distance r on the balancer weight 32 side.
₀ , the distance on the needle bar 44 side is different from the distance r. Others are the same as those in FIG. 3 of the first embodiment, and the following relationships are established as in the first embodiment.

The crank ratio λ is λ = r / L = r ₀ / L _{0 The} exciting force f generated by the reciprocating linear motion of the needle bar 44 or the like is

[0046]

[Equation 8]

The exciting force f ₀ generated by the reciprocating linear movement of the balancer weight 32 is

[0048]

[Equation 9]

The sum of the exciting forces in the vertical direction is

[0050]

[Equation 10]

If the mass m ₀ ≈rm / r ₀ of the balancer weight 32 is set so that mr = m ₀ r ₀ , the exciting force in the linear direction becomes completely zero. Also, in the case of r / L≈r ₀ / L ₀ and m ₀ ≈rm / r ₀ , the exciting force is extremely small. The centrifugal force generated around the upper shaft 10 is the same as in the first embodiment.

Needle bar crank 54 of the system of the second embodiment
Is manufactured with the distance r ₀ shorter than the distance r, the amount of movement of the balancer weight 32 is small. Therefore, there is an advantage that the frame itself of the sewing machine can be downsized. Further, since the needle bar crank 54 of the second embodiment is a single member, it can be made stronger than the balanced crank 12 and the needle bar crank 13 of the first embodiment, which is composed of two members. It is easily possible.

Incidentally, the mass of the portion of the needle bar 44, etc. which makes a reciprocating linear motion means the needle bar 44, the needle bar holder 46, the needle bar thread guide 4
8, the needle 50, and the mass around the bearing portion of the needle bar connecting rod 36 on the needle bar 44 side are shown.

In the first and second embodiments, the motion of the balancer weight 32 is restricted to the vertical motion, but a mechanism for restricting the motion of the member corresponding to the balancer weight 32 to the swing motion is shown in FIG. A third embodiment will be described below with reference to FIGS.

A swing shaft 80 fixed to a sewing machine frame (not shown) and a counterbalance crank 7 provided on the upper shaft 10.
2a, 72b, a balance connecting rod 74 rotatably supported by the counter crank 73, a rotatably supported by the other end of the counter connecting rod 74 and a swing shaft 80. The swing arm 76 forms a four-bar linkage. Therefore, the balance connecting rod 74 swings in the arrow direction shown in FIG. 7, with the swing arm 76 and the swing shaft 80 restricting the direction of movement.

The upper shaft 1 is attached to the other end of the counter crank 72b.
One end of the connecting shaft 82 is fixed so as to have the same axis center as that of 0, and the balance crank 72 is attached to the other end of the connecting shaft 82.
One end of the needle bar crank 73 extending in the opposite direction (180 degrees) from a and 72b is fixed. Therefore, the connecting shaft 82 and the needle bar crank 73 rotate together with the upper shaft 10.
Further, a needle bar 44 is swingably attached to the other end of the needle bar crank 73 via a needle bar connecting rod 84 and a needle bar holder 44, and other configurations are the same as those of the first and second embodiments. Similar to the example.

The position of the center of gravity of the balancing connecting rod 74 is such that the balancing connecting rod 74 and the swing arm 76 are
Connecting rod 7 to match the axis of rotation of
4 is determined, and the shape of the counter cranks is determined so that the gravity center positions of the counter cranks 72a and 72b coincide with the axis of the upper shaft 10. Furthermore, the counter crank 72
Since the swing arm 3 is sufficiently longer than the arm lengths r ₀ of a and 72b and the swing arm 80 is arranged so as to be substantially horizontal, the center of gravity of the balancing connecting rod 74 is set in the vertical direction. Performs almost linear motion. The mass of the balancing connecting rod 74 corresponds to the mass of the balancer weight 32 of the first embodiment.

In the mechanism having the above structure, the upper shaft 1
When 0 rotates, the needle bar 44 and the center of gravity of the balancing connecting rod 74 move in opposite directions, so that the above equation holds and the inertial force associated with the reciprocating motion of the needle bar is canceled.

Further, since the horizontal movement of the center of gravity connecting rod 74 and the swing arm 76 of the balance connecting rod 74 is small, the inertial force associated therewith can be almost ignored. Further, since the shape of the balance cranks 72a and 72b is determined so that the center of gravity of the balance cranks 72a and 72b coincides with the axial center of the upper shaft 10, the balance cranks 72a and 72b are formed.
The centrifugal force due to the movement of does not occur.

In the first to third embodiments, since the vertical inertial force generated by the reciprocating motion of the needle bar is completely canceled, the vibration of the sewing machine is prevented. Along with this, it is possible to perform accurate sewing on the workpiece and reduce noise due to vibration. For the operation of the balancer weight 32 and the balancing connecting rod 74,
Since the crank mechanism is used instead of gear transmission, no noise such as gear noise is generated and it is quiet.

In the first to third embodiments, the phase shift between the balancer weight 32 moved by the crank and the object corresponding thereto and the needle bar 44 is set to 150 degrees to 210 degrees. The effect is obtained, but 18
When it is 0 degree, the vibration can be suppressed most.

The crank mechanism for canceling the exciting force may be provided not on the upper shaft 10 directly but on a shaft which rotates in synchronization with the upper shaft 10 via a gear. In this case, the degree of freedom in arranging the crank mechanism with other devices in the frame of the sewing machine is increased. Further, depending on the arrangement of the crank mechanism and other devices in the frame of the sewing machine, the trajectory of the balancer weight 32 may be another trajectory that moves in a substantially straight line.

[0063]

As is apparent from the above description,
In the sewing machine of the present invention, the balance member moved by the crank with a phase difference with the needle bar can completely cancel out the inertial force associated with the reciprocating motion of the upper shaft, so that the vibration of the sewing machine is reduced, Quiet and accurate sewing is possible.

[Brief description of drawings]

FIG. 1 is an explanatory view of a crank mechanism of the present invention.

FIG. 2 is an explanatory diagram of a crank mechanism of the present invention.

FIG. 3 is an assembly diagram of the crank mechanism of the present invention.

FIG. 4 is an explanatory diagram of a crank mechanism of the present invention.

FIG. 5 is an assembly diagram of the crank mechanism of the present invention.

FIG. 6 is an explanatory diagram of a crank mechanism of the present invention.

FIG. 7 is an assembly diagram of the crank mechanism of the present invention.

FIG. 8 is an upper shaft mechanism diagram of a conventional sewing machine.

FIG. 9 is an upper shaft mechanism diagram of a conventional sewing machine.

[Explanation of symbols]

 10 Upper shaft 12 Balancing crank 13 Needle bar crank 26 Balancing connecting rod 32 Balancer weight 33 Slide guide 36 Needle bar connecting rod 44 Needle bar

Claims (4)

[Claims] 1. A sewing machine that performs sewing by vertically reciprocally moving a needle bar through a needle bar crank by rotation of an upper shaft for sewing, wherein a balance crank having a phase difference from the needle bar crank, and the balance crank. A sewing machine comprising: a balance member that is rotatably supported; and a regulation member that regulates the movement of the balance member to a constant value. 2. The sewing machine according to claim 1, wherein the movement of the balancing member is restricted to a swinging motion by the restriction member. 3. The sewing machine according to claim 1, wherein the movement of the balancing member is restricted to a linear movement by the restriction member. 4. The sewing machine according to claim 1, wherein the counterbalance crank is fixed to the upper shaft.